As the high definition (HD) display format becomes more popular, consumers are purchasing high definition equipment, such as HD displays and HD set top boxes, to view high quality content. However, most content is currently available only in standard resolution interlaced video, and needs to be converted to be displayed in an HD format. For example, a typical home theater system may be based on Digital Video Disc (DVD) materials. In a home theater system, low-resolution video sequences are reconstructed by decoding MPEG compressed video streams, then further processed with special signal processing circuitry that performs video up-scaling.
A special situation arises when interlaced video originating from film sources are converted to progressive frames. Film sources, such as motion pictures, are truly progressive in nature, since film comprises numerous still images displayed in rapid succession to create the illusion of motion. For example, typical films shown in movie theaters are displayed at approximately 24 frames per second (actually 23.976 frames per second). To display progressive film content in the NTSC format of approximately 60 interlaced fields per second (actually 59.94 fields per second), the film is converted to an interlaced format using a technique known as 3:2 pulldown. Once the film is converted to an interlaced format, the interlaced format may be converted to a high definition format.